Phalange resection instrument

Abstract

To provide a phalange resection instrument suitable for resection of a phalanx.SOLUTION: A phalange resection instrument 1 includes a rotary shaft 2 and a cutting portion 3 located at one end 4 of the rotary shaft 2. The rotary shaft 2 has a first through hole 6 extending in a front-rear direction 91. The cutting portion 3 includes four blades 10 that each intersect an axis line L and extend radially from the rotary shaft 2 with a spacing in a circumferential direction about the axis line L, and an annular frame 11 that connects outer ends 18 of the four blades 10. The frame 11 is positioned on a rear side relative to cutting edges 13 of the four blades 10.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a phalangeal resection tool used in artificial finger joint replacement surgery and the like. [Background technology]

[0002] Patent Document 1 discloses a method for flattening the glenoid cavity of a shoulder joint by rotating a circular reamer connected to a power connection means using the power means to bring the cutting surface into contact with the bone. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2019-155192 Summary of the Invention [Problem to be solved by the invention]

[0004] In artificial joint replacement surgery, it is necessary to attach the implant in a precise position to ensure smooth joint movement after surgery. To achieve this, the surgeon must cut the bone to precise dimensions and ensure a smooth cutting surface. However, when cutting relatively small bones such as phalanges, cutting tools that use the same structure as cutting tools used in conventional shoulder joints and hip joints but adapted to the size of phalanges have a problem in that the cutting edge does not easily penetrate the bone. As a result, the surgeon must press the cutting edge against the phalanges with great force, placing a heavy burden on the surgeon.

[0005] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a phalangeal resection tool suitable for resecting phalanges. [Means for solving the problem]

[0006] (1) The phalangeal resection tool according to the present invention comprises a rotating shaft and a cutting portion located at one end of the rotating shaft. The rotating shaft has a through hole extending in the axial direction. The cutting portion has two or more blades, but not more than four, that intersect with the axis and extend radially from the rotating shaft at circumferential intervals, and an annular frame connecting the outer ends of the two or more blades. The frame is located closer to the other end of the rotating shaft than the cutting edges of the two or more blades, but not more than four.

[0007] The above configuration is suitable for cutting relatively small phalanges, and the cutting edge easily bites into the phalanges. A steel wire that acts as a guide is inserted into the through-hole of the rotating shaft. The cut bone fragments easily pass through the space between the blades and are ejected from the cutting section. The frame prevents surrounding tissue from getting caught in the blade.

[0008] (2) The cutting edge may be continuous with the periphery of the through hole.

[0009] According to the above configuration, the phalanges are also cut around the through holes, so that the holes drilled in the phalanges for inserting the steel wires that serve as guides can be small.

[0010] (3) The outer diameter of the frame may be 1.3 times or more and less than 4.0 times the outer diameter of the rotating shaft.

[0011] According to the above configuration, the strength of the rotation shaft is maintained while ensuring the inner diameter of the through hole, making it particularly suitable for cutting phalanges.

[0012] (4) The dimension of the frame in the direction along the axis may be equal to or smaller than the dimension of the blade in the direction along the axis.

[0013] According to the above configuration, the cut bone fragments can easily come out of the frame, which prevents the frame from becoming clogged with bone fragments and making cutting impossible.

[0014] (5) The cutting edges may be positioned at equal intervals in the circumferential direction.

[0015] According to the above configuration, the rotational torque of the rotary shaft is transmitted evenly to each cutting edge.

[0016] (6) The cutting edge may extend in a direction perpendicular to the rotation axis.

[0017] According to the above configuration, it is easy to form a flat cutting surface.

[0018] (7) The cutting edge may extend linearly and be located on an imaginary line connecting the axis and the frame when viewed from the axial direction.

[0019] According to the above configuration, the cutting edge passes through the axis and extends linearly in a direction perpendicular to the axis, which allows the length of the cutting edge to be made as short as possible, thereby reducing the contact area with the bone.

[0020] (8) The cutting edge may be located on an imaginary plane perpendicular to the axis, and the imaginary plane may be located at the tip of the cutting part on the opposite side to the rotation axis.

[0021] (9) The blade has a concave surface extending from the cutting edge at a position opposite to the direction of rotation of the cutting edge, and the concave surface is inclined from the cutting edge toward the rotation axis.

[0022] According to the above configuration, the phalanges can be smoothly cut.

[0023] (10) The rotation shaft may be located radially inward of the spaces between the four or less but two or more blades.

[0024] (11) A part of an opening on the cutting edge side of the space between the four or less but two or more blades may be located radially inward from an outer surface of the rotary shaft.

[0025] According to the above configuration, the cut bone fragments can easily enter between the blades.

[0026] (12) The openings on the opposite side of the cutting edge of the space between the four or less but two or more blades may have a total area surrounded by the edges of the openings on an imaginary plane perpendicular to the axis that is 25% or more of the area surrounded by the outer peripheral surface of the frame on the imaginary plane.

[0027] According to the above configuration, the cut bone fragments can be easily removed from the frame, making it difficult for the bone fragments to become stuck inside the frame. [Effects of the Invention]

[0028] According to the present invention, a phalangeal resection tool suitable for resecting a phalange is realized. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a perspective view showing an example of a finger bone resection tool 1 according to this embodiment, together with a proximal phalanx 50 on the proximal interphalangeal joint side. [Figure 2] FIG. 2 is a perspective view showing an example of the phalangeal resection tool 1 according to this embodiment. [Figure 3] FIG. 3 is a view of the phalange resection tool 1 shown in FIG. 2 as seen from the left. [Figure 4] FIG. 4 is a front view of the phalange resection tool 1 shown in FIG. [Figure 5] FIG. 5 is a diagram for explaining the procedure for placing the steel wire 70 on the bone shaft 55. As shown in FIG. [Figure 6] FIG. 6 is a diagram for explaining the procedure for cutting the femoral head 53 with the phalangeal resection tool 1. FIG. [Figure 7] FIG. 7 is a diagram for explaining the procedure for cutting the femoral head 53 with the phalangeal resection tool 1. FIG. [Figure 8] FIG. 8 is a diagram showing a cutting surface 57 formed by the phalangeal resection tool 1. As shown in FIG. [Figure 9] FIG. 9 is a diagram for explaining a procedure for placing the proximal phalanx side implant 78 in the proximal phalanx 50. [Figure 10]FIG. 10(a) is a view of a phalange resecting tool 1A according to the first modification as seen from the oblique front, and FIG. 10(b) is a view as seen from the oblique rear. [Figure 11] FIG. 11 is a view of a phalange resecting tool 1A according to the first modification, viewed from the left. [Figure 12] FIG. 12(a) is a view of a phalange resecting tool 1B according to the second modification as viewed from the left, and FIG. 12(b) is a view as viewed obliquely from the front. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings as appropriate. Note that the embodiment described below is merely an example of the present invention, and it goes without saying that the embodiment of the present invention can be appropriately modified without departing from the spirit and scope of the present invention.

[0031] In the following description, as shown in Figures 1 and 2, the direction in which two of the four cutting edges 13 of the phalange resection tool 1 that face each other with respect to the axis L extends is defined as the up-down direction 90. The front-rear direction 91 is defined as the direction perpendicular to the up-down direction 90 and as the direction in which the axis L extends. The side of the rotation shaft 2 where the cutting unit 3 is located is defined as the front, and the opposite side is defined as the rear. The left-right direction 92 is defined as the direction perpendicular to the up-down direction 90 and the front-rear direction 91. When viewing the cutting unit 3 from the rear, the direction along the cutting edge 13 located to the right of the upper and lower cutting edges 13 is defined as the right, and the direction along the cutting edge 13 located to the left is defined as the left.

[0032] As shown in FIG. 1 , the phalangeal resection tool 1 is an instrument used to cut the phalanges, which are bones of the fingers. The phalangeal resection tool 1 is used, for example, in artificial finger joint replacement surgery for the phalanges. Artificial finger joint replacement surgery is one of the treatments performed when the condyle 51 of a finger joint and the glenoid cavity in which the condyle 51 slides are no longer able to perform their original joint functions due to osteoarthritis, rheumatoid arthritis, or the like. In artificial finger joint replacement surgery, a proximal phalangeal implant 78 (see FIG. 9 ) made of a metal such as a titanium alloy or a cobalt-chromium alloy or a resin is placed. Although not shown, the proximal phalangeal implant 78 has a fixing member that fixes the proximal phalangeal implant 78 to the proximal phalange 50. The fixing member can be fitted into the bone hole 56 in the proximal phalange 50, which is indicated by the dashed line in FIG. 8 .

[0033] A rotational force is applied to the phalangeal resection tool 1 by a power means (not shown). The phalangeal resection tool 1 is made of metal such as stainless steel. The phalangeal resection tool 1 has a rotation shaft 2 and a cutting part 3. When cutting the proximal phalange 50, the phalangeal resection tool 1 rotates counterclockwise R1 around the steel wire 70 when viewed from the front.

[0034] As shown in FIGS. 2 and 3, the rotating shaft 2 has a cylindrical shape. At a rear end 8 (an example of the other end), the rotating shaft 2 has an outer peripheral surface 7 (an example of an outer surface) clamped by a power unit. As shown by the dashed line in FIG. 3, the rotating shaft 2 has a first through hole 6 (an example of a through hole) formed along the axis L. The central axis of the rotating shaft 2 coincides with the axis L. The first through hole 6 is circular when viewed from the front-rear direction 91 and is a hole extending along the axis L. A steel wire 70, which will be described later, is inserted through the first through hole 6. Therefore, the inner diameter of the first through hole 6 is larger than the outer diameter of the steel wire 70 (see FIG. 1). For example, the outer diameter of a typical steel wire 70 is approximately 1.1 to 1.6 mm. Therefore, the inner diameter of the first through hole 6 is, for example, approximately 1.2 to 1.8 mm. The outer diameter of the rotating shaft 2 is set so as to have sufficient strength against the rotational torque applied to the rotating shaft 2. For example, the outer diameter of the rotating shaft 2 is within a range of 3.0 to 6.4 mm. In this case, the outer peripheral surface 7 of the rotating shaft 2 is located radially inward about the axis L with respect to the space S located between adjacent blades 10 in the circumferential direction about the axis L among the four blades 10. Therefore, bone chips generated by cutting can easily come out of the space S.

[0035] The cutting portion 3 is continuous with one end 4 of the rotating shaft 2. As shown in FIGS. 3 and 4 , the cutting portion 3 has four blades 10, a frame 11, and a second through hole 12. Each of the four blades 10 extends in a direction perpendicular to the axis L. The four blades 10 are positioned at equal intervals with a space S in the circumferential direction centered on the axis L. Adjacent blades 10 in the circumferential direction are positioned at 90° intervals. The second through hole 12 is circular when viewed from the front-rear direction 91 and extends along the axis L. The central axis of the second through hole 12 coincides with the axis L. The second through hole 12 is continuous with the first through hole 6. The inner diameter of the second through hole 12 is the same as the inner diameter of the first through hole 6. The second through hole 12 opens forward. The four blades 10 each extend radially from a periphery 16 of the second through hole 12. Each blade 10 is connected to one end 4 of the rotating shaft 2 at a portion close to the axis L.

[0036] The four blades 10 have the same shape but are arranged differently. The blade 10 has a cutting edge 13 located at its front end. The cutting edge 13 is the portion that cuts the phalanges. The cutting edge 13 extends linearly from the periphery 16 of the second through hole 12 to the outer end 18 of the blade 10. The cutting edges 13 are positioned at equal intervals in the circumferential direction, with a space S between them. As shown in FIG. 4 , two of the four cutting edges 13 that are not adjacent in the circumferential direction are positioned on an imaginary line L1 that is perpendicular to the axis L and connects the axis L and the frame 11. The remaining two cutting edges 13 are positioned on an imaginary line L2 that is perpendicular to the axis L and the imaginary line L1. Of the four cutting edges 13 that are not adjacent in the circumferential direction, one cutting edge 13 is positioned on an extension of the other cutting edge 13. The positional relationship of each cutting edge 13 with respect to non-adjacent cutting edges 13 in the circumferential direction is point symmetrical with respect to the axis L when viewed from the front-rear direction 91 (an example of an axial direction). Each cutting edge 13 is located on an imaginary plane P1 (shown by a two-dot chain line in FIG. 3) that is perpendicular to the front-rear direction 91. The imaginary plane P1 is located at the front end of the phalange resection tool 1.

[0037] As shown in Figures 2 and 4, the blade 10 has a first surface 14 (an example of a concave surface), a second surface 17, a third surface 20, and a fourth surface 23. The first surface 14 is a concave surface with respect to an imaginary plane P1, and extends backward while being inclined from the cutting edge 13. The first surface 14 is located on the clockwise side of the cutting edge 13 on the blade 10 when viewed from the front (see Figure 4). The first surface 14 is located on the blade 10 where the cutting edge 13 is formed, and is parallel to the cutting edge 13 when viewed from the front. The first surface 14 intersects with the front-rear direction 91.

[0038] The second surface 17 is located on the counterclockwise side of the cutting edge 13 when viewed from the front (see FIG. 4). The second surface 17 extends rearward from the cutting edge 13. The second surface 17 is located on the blade 10 where the cutting edge 13 is formed, and is parallel to the cutting edge 13 when viewed from the front. The second surface 17 extends from the cutting edge 13 along the front-rear direction 91.

[0039] The third surface 20 is a flat surface extending rearward from the rear end of the first surface 14. The third surface 20 is located on the blade 10 where the cutting edge 13 is formed, and is generally parallel to the cutting edge 13 when viewed from the front. The third surface 20 has a first portion 27 and a second portion 28 (see FIG. 2).

[0040] The first portion 27 is a surface of the blade 10 facing clockwise direction R2 and extends along the front-rear direction 91. The first portion 27 is parallel to the cutting edge 13 when viewed from the front. The first portion 27 faces the inner surface 22. The first portion 27 is continuous with the inner surface 22.

[0041] The second portion 28 is located radially inward about the axis L than the first portion 27. The second portion 28 faces the inner surface 22. The second portion 28 is continuous with the first portion 27 and the fourth surface 23. The second portion 28 is located radially outward from the outer peripheral surface 7 of the rotating shaft 2. The second portion 28 is inclined with respect to the first portion 27. More specifically, the second portion 28 extends from a position closest to the axis L in the first portion 27 on the blade 10 where the second portion 28 is located, while moving away from the cutting edge 13.

[0042] The fourth surface 23 is a flat surface that extends rearward from the rear end of the second surface 17 and extends radially of the axis L (see FIG. 2). The fourth surface 23 is a surface of each blade 10 that faces counterclockwise R1. The area of ​​the third surface 20 is larger than the area of ​​the fourth surface 23. The fourth surface 23, the first portion 27, the second portion 28, and the inner surface 22 have the same dimension in the front-to-rear direction 91. The fourth surface 23 is continuous with the inner surface 22.

[0043] The frame 11 has an annular shape centered in the front-rear direction 91. Four blades 10 extending from the periphery 16 of the second through-hole 12 are connected to the frame 11. The center of the frame 11 coincides with the axis L. The dimension of the frame 11 along the front-rear direction 91 is equal to or less than, and at least one-third of, the dimension of the blades 10 along the front-rear direction 91. This ensures the strength of the frame 11 while allowing the cut bone fragments to easily pass through the frame 11. The rear end of the frame 11 in the front-rear direction 91 coincides with one end 4 of the rotating shaft 2. The front end of the frame 11 is located rearward of the cutting edge 13 and is continuous with the first surface 14 and the second surface 17. The outer peripheral surface 25 of the frame 11 is continuous with the outer end 18 of the blade 10. The outer diameter of the frame 11 is within a range of 1.3 to 4 times the outer diameter of the rotating shaft 2.

[0044] As shown in FIGS. 3 and 4 , the space S is defined by the third and fourth surfaces 20 and 23 of two circumferentially adjacent blades 10 among the four blades 10 and the inner surface 22 of the frame 11. The four spaces S have the same size of edge 30 (see FIG. 2 ) when viewed from the front. The four spaces S also have the same size of edge 31 (see FIG. 1 ) when viewed from the rear. In this embodiment, the edges 30 and 31 have the same shape and size. The edges 30 and 31 are located radially outward from the outer peripheral surface 7 of the rotary shaft 2. The total area of ​​the regions enclosed by the four edges 31 on the imaginary plane P2 located at the rear end of the cutting unit 3 is within a range of 25% to 65% of the area of ​​the region enclosed by the outer peripheral surface 25 of the frame 11 on the imaginary plane P2. This ensures the strength of the frame 11 while allowing the cut bone fragments to easily pass through the frame 11.

[0045] [Procedure using phalangeal resection tool 1] In this embodiment, a procedure will be described in which a proximal phalanx side implant 78 is placed in the proximal phalanx 50 of the proximal interphalangeal joint. First, as shown in FIG. 5 , the surgeon inserts a steel wire 70 along the bone axis 55 of the proximal phalanx 50. A guide member may be used during insertion. In this case, the steel wire 70 is inserted into a through-hole formed in the guide member and driven into the femoral head 53. The steel wire 70 has a pointed tip, and the surgeon drives it from the femoral head 53 of the proximal phalanx 50 along the bone axis 55. The surgeon checks under X-ray fluoroscopy whether the steel wire 70 is inserted along the bone axis 55, and if there is any deviation, redoes the driving of the steel wire 70.

[0046] Next, as shown in Figures 6 and 7, the femoral head 53 is cut using the phalangeal resection tool 1 attached to a power unit (not shown). The surgeon inserts a steel wire 70 attached to the proximal phalange 50 through the second through-hole 12 and the first through-hole 6 of the phalangeal resection tool 1. This allows the phalangeal resection tool 1 to rotate while being positioned by the steel wire 70. With the cutting edges 13 facing the femoral head 53 of the proximal phalange 50, the surgeon applies a load to the power unit from behind to cut the proximal phalange 50 to the appropriate position. At this time, the four cutting edges 13 bite into and cut the femoral head 53, and the cut bone fragments enter the openings 15 and are ejected from the openings 21 to the rear of the cutting unit 3. Even if surrounding tissue comes into contact with the rotating cutting unit 3, the frame 11 abuts against the surrounding tissue. As shown in Figure 8, a cutting surface 57 perpendicular to the bone axis 55 is formed on the proximal phalange 50 cut by the cutting edges 13. The surgeon confirms that the cutting surface 57 is a flat surface perpendicular to the bone axis 55. The surgeon enlarges the hole 56a using an appropriate instrument to form the bone hole 56 into which the fixation member will be inserted. The surgeon temporarily places a trial (not shown) on the cutting surface 57 to confirm that the bone hole 56 has been properly formed, and then places the proximal phalanx side implant 78 (see Figure 9). Although not shown, the surgeon also places the middle phalanx side implant, checks the movement of the proximal interphalangeal joint, and if there are no problems, closes the incision and completes the artificial finger joint replacement procedure.

[0047] [Effects of this embodiment] According to this embodiment, the number of blades 10 is four, which is relatively small. Therefore, the contact area with the proximal phalanx 50 is not too large, and the cutting edge 13 can easily dig into the proximal phalanx 50. Therefore, this is suitable for cutting the relatively small proximal phalanx 50. Furthermore, the first through-hole 6 penetrates the rotating shaft 2, allowing a steel wire 70 to be inserted as a guide during cutting, thereby preventing the phalangeal resection tool 1 from shifting from the femoral head 53 during cutting. Because a space S is provided between adjacent blades 10 in the circumferential direction among the four blades 10, cut bone fragments can easily pass through this space S and be expelled. This prevents bone fragments generated during cutting from accumulating on the cutting edge 13 and making continuous cutting difficult. Furthermore, the ring-shaped frame 11 connecting the outer ends 18 of the four blades 10 prevents surrounding tissue from becoming entangled in the blades 10 while cutting the bone.

[0048] According to this embodiment, the cutting edge 13 is continuous with the periphery 16 of the second through-hole 12. Therefore, the vicinity of the bone axis of the proximal phalanx 50 is also cut by the cutting edge 13. Therefore, the hole drilled in advance in the proximal phalanx 50 for inserting the steel wire 70 as a guide may be small.

[0049] According to this embodiment, the outer diameter of the steel wire 70 is relatively small, about 1.1 to 1.6 mm, and the outer diameter of the rotating shaft 2 is larger than one-fourth the outer diameter of the frame 11. As a result, the inner diameter of the first through-hole 6 is ensured, while the thickness of the rotating shaft 2 is also ensured, maintaining strength. This makes it possible to realize a phalange resection tool 1 that is particularly suitable for cutting phalanges. Furthermore, because the outer diameter of the rotating shaft 2 is 1.3 or less of the outer diameter of the frame 11, bone fragments are discharged through the space S without accumulating on the cutting edge 13.

[0050] According to this embodiment, the dimension of the frame 11 in the front-rear direction 91 is equal to or smaller than the dimension of the blade 10, so that bone fragments cut by the cutting edge 13 can easily pass rearward through the frame 11. This prevents bone fragments from getting stuck inside the frame 11, making cutting impossible.

[0051] According to this embodiment, the cutting edges 13 of the four blades 10 are positioned at equal intervals in the circumferential direction. Therefore, the rotational torque of the rotating shaft 2 is transmitted evenly to each cutting edge 13 without bias, and the head 53 of the proximal phalanx 50 is cut flat. Cutting the head 53 flat prevents the proximal phalanx side implant 78 from being placed in a floating state above the cutting surface 57 or from being damaged by sliding and applying local loads.

[0052] According to this embodiment, the cutting edges 13 of the four blades 10 are perpendicular to the axis L, which makes it easier for the surgeon to apply an even load to the femoral head 53 during cutting and to form a flat cutting surface 57. This makes it easier for the surgeon to form a hole in the correct direction using the flat cutting surface 57 as a reference.

[0053] According to this embodiment, the cutting edge 13 passes through the axis L and extends linearly in a direction perpendicular to the axis L. This allows the length of the cutting edge 13 to be made as short as possible. As a result, the frictional force between the cutting edge 13 and the bone during cutting is reduced, reducing the burden on the surgeon.

[0054] According to this embodiment, when a load is applied to the phalange resection tool 1 during cutting, only the cutting edge 13 comes into contact with and bites into the cutting surface 57, so that the cutting surface 57 can be smoothly cut.

[0055] [Variation 1] In the above-described embodiment, an example has been described in which the outer peripheral surface 7 of the rotating shaft 2 is located radially inward of the space S, but this configuration is not limiting. As shown in Figs. 10 and 11, in the phalangeal resection tool 1A, part of the space S may be located radially inward of the outer peripheral surface 7 of the rotating shaft 2.

[0056] 10(a), the blade 10 has a first surface 14, a second surface 17, a third surface 20, a fourth surface 23, and a fifth surface 24. Regarding the first surface 14, the second surface 17, the third surface 20, and the fourth surface 23, descriptions of the same configurations as those in the above-described embodiment will be omitted.

[0057] The third surface 20 is a surface of each blade 10 facing clockwise direction R2. The third surface 20 is located on the blade 10 where the cutting edge 13 is formed, and is parallel to the cutting edge 13 when viewed from the front. The third surface 20 is perpendicular to the fourth surface 23.

[0058] The fifth surface 24 is a part of one end 4 of the rotating shaft 2 and is exposed to the space S. The fifth surface 24 is a flat surface that is continuous with the rear end of the third surface 20 and the rear end of the fourth surface 23. The fifth surface 24 is a surface that faces forward. The radial outer end of the fifth surface 24 is part of the front end of the outer circumferential surface 7. The fifth surface 24 defines a rear and radially inner portion of the space S.

[0059] The space S has an opening 15A located in the front and an opening 21A (an example of an opening on the side opposite to the cutting edge) located in the rear (see FIG. 10(b)). The edges 30A of the four openings 15A have the same size when viewed from the front. The edges 30A are located at the front end of the frame 11.

[0060] A portion of the opening 21A is defined by the outer peripheral surface 7 of the rotating shaft 2. When viewed rearward from the opening 15A (see FIG. 10(a)), a fifth surface 24 of the space S is visible. That is, in the space S, an inner space 32 (an example of a portion of an opening), which is a portion of the opening 15A on the cutting edge 13 side, is located radially inward of the outer peripheral surface 7 of the rotating shaft 2.

[0061] The edges 31A of the four openings 21A have the same size when viewed from behind. The edges 31A are located at the rear end of the cutting part 3 and are located on an imaginary plane P2 (see FIG. 11) that is perpendicular to the front-rear direction 91 at the rear end of the cutting part 3.

[0062] According to this first modification, opening 15A is wider radially inward than opening 21A when viewed from the front. This makes it easier for cut bone fragments to enter between the blades 10. In this first modification, narrowing opening 21A allows the outer diameter of rotating shaft 2 to be increased, so that sufficient strength of rotating shaft 2 can be ensured even when using steel wire 70 that is thick and difficult to bend. This allows for stable cutting.

[0063] According to the present modification 1, because the edge 31A of the cutting portion 3 is equal to or larger than a predetermined size, bone chips cut by the cutting edge 13 can easily pass through the opening 21A and slip backward. This makes it difficult for bone chips to become stuck inside the frame 11.

[0064] [Variation 2] In the first modified example, the fifth surface 24 is a part of one end 4 of the rotating shaft, and is a flat surface extending in the up-down direction 90 and the left-right direction 92. However, the present invention is not limited to this configuration. As shown in FIGS. 12(a) and 12(b), the fifth surface 24B of the phalange resection tool 1B may be recessed rearward from one end 4 of the rotating shaft 2. In other words, the fifth surface 24B may be a curved surface. The fifth surface 24B forms a space at one end 4 of the rotating shaft 2 that is open forward and radially outward.

[0065] According to the present second modification, by recessing the fifth surface 24B rearward, bone chips generated by cutting can be more easily expelled.

[0066] [Other variations] In the above embodiment, the cutting portion 3 has four blades 10 positioned at equal intervals in the circumferential direction around the axis L, but this configuration is not limiting. Three or two blades 10 may be arranged in the circumferential direction around the axis L.

[0067] In the above embodiment, the cutting edge 13 extends linearly from the circumferential edge 16 of the second through hole 12 to the outer end of the blade 10, but this configuration is not limiting. The cutting edge 13 may not be continuous with the circumferential edge 16 of the second through hole 12, and may be located radially outward from the circumferential edge 16. Furthermore, the cutting edge 13 does not necessarily need to extend to the outer end 18 of the blade 10, and may be located, for example, radially inward from the outer end 18 of the blade 10 or the frame 11.

[0068] In the above embodiment, a case has been described in which two of the four cutting edges 13 that are not adjacent to each other in the circumferential direction about the axis L are located on an imaginary straight line L1, and the remaining two cutting edges 13 are located on an imaginary straight line L2. Also, a case has been described in which the four cutting edges 13 are located on an imaginary plane P1 that is perpendicular to the front-rear direction 91 at the front end of the phalange resection tool 1. However, the four cutting edges 13 are not limited to this configuration. The four cutting edges 13 are located on the imaginary straight lines L1 and L2 when viewed from the front, but may not be located on the imaginary straight lines L1 and L2 when viewed from a direction perpendicular to the front-to-rear direction 91, and may be located further forward than the imaginary straight lines L1 and L2. In other words, the four cutting edges 13 only need to be located on the imaginary straight lines L1 and L2 when viewed from the front (direction along the axis L).

[0069] In the above embodiment, two of the four cutting edges 13 that are not adjacent in the circumferential direction are located on the imaginary line L1, and the remaining two cutting edges 13 are located on the imaginary line L2. However, this configuration is not limiting. For example, these four cutting edges 13 may be located on an imaginary line that is not located on the imaginary line L1 or L2 when viewed from the front-rear direction 91, but on a imaginary line that connects the periphery 16 and the frame 11. In other words, the cutting edges 13 do not have to extend so as to connect the periphery 16 and the frame 11 over the shortest distance.

[0070] In the above embodiment, the case where the outer diameter of the frame 11 is 1.3 times or more and less than 4 times the outer diameter of the rotating shaft 2 has been described as an example, but this is not limiting. The outer diameter of the frame 11 may be less than 1.3 times the outer diameter of the rotating shaft 2, or may be 4 times or more.

[0071] In the above-described embodiment, the frame 11 has been described as having a circular ring shape, but the present invention is not limited to this configuration. The frame 11 may have any shape as long as it does not damage surrounding tissues when rotated, and the outer shape of the frame 11 is smooth.

[0072] In the above embodiment, the rotating shaft 2 is described as having a cylindrical shape, but the present invention is not limited to this configuration. The rotating shaft 2 may have, for example, a rectangular cylindrical shape.

[0073] In the above embodiment, the cutting edges 13 of the four blades 10 are positioned at equal intervals in the circumferential direction around the axis L, but this is not the only possible configuration. The cutting edges 13 may be positioned at different intervals in the circumferential direction.

[0074] In the above embodiment, an example has been described in which only one bone hole 56 for inserting a fixation member is provided on the cutting surface 57 of the proximal phalanx 50, but the shape and number of the bone hole 56 are not limited to this configuration. The proximal phalanx side implant 78 may have two or more fixation members, and the surgeon may provide two or more bone holes 56 on the cutting surface 57 and install the proximal phalanx side implant 78. This prevents the proximal phalanx side implant 78 from shifting around the fixation member after installation.

[0075] In the above embodiment, the phalangeal resection tool 1 has been described as being used to cut the proximal phalange 50 in artificial finger joint replacement surgery, but the present invention is not limited to this configuration. The phalangeal resection tool 1 may also be used to cut the middle phalange, distal phalange, or metacarpal bone other than the proximal phalange 50.

[0076] In the above embodiment, the phalangeal resection tool 1 has been described as rotating around the steel wire 70 in a counterclockwise direction R1 when viewed from the front to cut the proximal phalanx 50, but this configuration is not limiting. The phalangeal resection tool 1 may also be configured to rotate in the opposite direction (clockwise direction R2) to cut the proximal phalanx 50. In other words, when viewed from the front, the first surface 14 may be positioned counterclockwise R1 relative to the cutting edge 13, and the second surface 17 may be positioned clockwise R2 relative to the cutting edge 13 (see FIG. 4).

[0077] In the above-described embodiment, the phalangeal resection tool 1 is made of a metal such as stainless steel, but the present invention is not limited to this configuration. The phalangeal resection tool 1 may be made of a resin or the like. Furthermore, the phalangeal resection tool 1 does not necessarily have to be made of a single material, and may be made of, for example, a metal portion and a resin portion.

[0078] In the above-described embodiment, an example was described in which the inner diameter of the second through hole 12 is the same as the inner diameter of the first through hole 6, but this configuration is not limited to this. The second through hole 12 may be larger or smaller than the inner diameter of the first through hole 6. The inner diameters of the first through hole 6 and the second through hole 12 need only be such that the steel wire 70 can be inserted therethrough and the phalangeal resection tool 1 can rotate. Note that by making the inner diameter of the second through hole 12 smaller, the cutting edge 13 can be positioned closer to the axis L, making it possible to cut to a position close to the axis L of the phalangeal resection tool 1.

[0079] In the above embodiment, the four blades 10 have the same shape but are arranged differently, but this is not limiting. The four blades 10 may have different shapes.

[0080] In the above embodiment, the shape of the cutting edge 13 is described as extending linearly when viewed from the front-rear direction 91, but this is not limiting. The shape of the cutting edge 13 may be, for example, an arc or curved shape when viewed from the front-rear direction 91, or any other shape that can cut the phalanges.

[0081] In the above-described embodiment, the first surface 14 is a concave surface with respect to the imaginary plane P1, and extends rearward while sloping from the cutting edge 13. However, the present invention is not limited to this configuration. The first surface 14 may be, for example, a plane that extends rearward from the position of the cutting edge 13 and expands along the front-to-rear direction 91. In this case, the second surface 17 may extend rearward while sloping counterclockwise from the cutting edge 13 when viewed from the front.

[0082] In the above embodiment, the second surface 17 extending rearward from the cutting edge 13 is aligned along the front-rear direction 91, but the present invention is not limited to this configuration. The second surface 17 may intersect with the front-rear direction 91.

[0083] In the above embodiment, the third surface 20 extends rearward from the rear end of the first surface 14 and is aligned along a plane that extends in the front-to-rear direction 91 and in the radial direction about the axis L, but the present invention is not limited to this configuration. The third surface 20 may extend rearward from the rear end of the first surface 14 and be inclined in a clockwise direction R2 when viewed from the front. Furthermore, the fourth surface 23 extends rearward from the rear end of the second surface 17 and is aligned along the radial direction of the axis L, but the present invention is not limited to this configuration. The fourth surface 23 may extend rearward from the rear end of the second surface 17 and be inclined in a counterclockwise direction R1 when viewed from the front.

[0084] In the above embodiment, the case where the edges 30 of the four openings 15 have the same size when viewed from the front has been described as an example, but the present invention is not limited to this configuration. The edges 30 may have different sizes when viewed from the front.

[0085] In the above embodiment, the case where the edges 31 of the four openings 21 have the same size when viewed from behind has been described as an example, but this is not limiting. The edges 31 may have different sizes when viewed from behind. [Explanation of symbols]

[0086] 1... Phalangectomy tool 2. Rotation axis 3...Cutting part 4...one end 6. First through hole (through hole) 7...Outer surface (outer surface) 8 Rear end (other end) 10 blades 11... frame 12... Second through hole (through hole) 13 Cutting edge 14...1st surface (concave) 15,15A,15B...Aperture 16. Periphery 18...outer end 21, 21A... Opening (opening on the side opposite to the cutting edge 13) 25...Outer surface 31, 31A... Edge (edge ​​of opening 21, 21A) 32: Inner space (part of opening 15A)

Claims

1. A rotation axis; a cutting portion located at one end of the rotary shaft, The rotating shaft has a through hole extending in the axial direction, The cutting part is Two or more but not more than four blades each intersecting the axis and extending radially from the rotation axis at circumferential intervals; and an annular frame connecting outer ends of the four or less but two or more blades, The frame is a phalange resection tool located on the other end side of the rotation shaft relative to the cutting edges of the four or less but two or more blades.

2. The phalangeal bone resection tool according to claim 1 , wherein the cutting edge is continuous with the periphery of the through hole.

3. 3. The phalangeal resection tool according to claim 1, wherein the outer diameter of the frame is 1.3 times or more and less than 4 times the outer diameter of the rotary shaft.

4. 3. The phalangeal resection tool according to claim 1, wherein the dimension of the frame in the axial direction is equal to or smaller than the dimension of the blade in the axial direction.

5. The phalangeal bone resection tool according to claim 1 or 2, wherein the cutting edges are positioned at equal intervals in the circumferential direction.

6. 3. The phalangeal resection tool according to claim 1, wherein the cutting edge extends in a direction perpendicular to the rotation axis.

7. 3. The phalangeal resection tool according to claim 1, wherein the cutting edge extends linearly and is located on an imaginary line connecting the axis and the frame when viewed from the axial direction.

8. The cutting edge is located on a virtual plane perpendicular to the axis, 3. The phalangeal resection tool according to claim 1, wherein the imaginary plane is located at the tip of the cutting portion on the opposite side to the rotation axis.

9. The blade has a concave surface extending from the cutting edge at a position opposite to a rotation direction of the cutting edge, 3. The phalangeal bone resection tool according to claim 1, wherein the concave surface is inclined from the cutting edge toward the rotation axis.

10. The phalangeal resection tool according to claim 1 or 2, wherein the rotation axis is located radially inward of the spaces between the four or less but two or more blades.

11. The phalangeal resection tool according to claim 1 or 2, wherein a part of the opening on the cutting edge side of the space between the four or less but two or more blades is located radially inward from the outer surface of the rotating shaft.

12. A finger bone resection tool as described in claim 1 or 2, wherein the openings on the opposite side of the cutting edge of the space between the four or less but two or more blades have a total area surrounded by the edges of the openings on an imaginary plane perpendicular to the axis that is 25% or more of the area surrounded by the outer peripheral surface of the frame on the imaginary plane.

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